Expose component_attributes on Schema. (#623) r=nalexander

Some parts of the query engine and transactor need to know whether an
attribute is a component attribute, and sometimes want to do so in
a generated SQL query. This is one way to do that.

core/src/lib.rs

@@ -809,6 +809,10 @@ pub struct Schema {
     /// Invariant: key-set is the same as the key-set of `entid_map` (equivalently, the value-set of
     /// `ident_map`).
     pub attribute_map: AttributeMap,
+
+    /// Maintain a vec of unique attribute IDs for which the corresponding attribute in `attribute_map`
+    /// has `.component == true`.
+    pub component_attributes: Vec<Entid>,
 }
 
 pub trait HasSchema {
@@ -826,9 +830,17 @@ pub trait HasSchema {
 
     /// Return true if the provided ident identifies an attribute in this schema.
     fn identifies_attribute(&self, x: &NamespacedKeyword) -> bool;
+
+    fn component_attributes(&self) -> &[Entid];
 }
 
 impl Schema {
+    pub fn new(ident_map: IdentMap, entid_map: EntidMap, attribute_map: AttributeMap) -> Schema {
+        let mut s = Schema { ident_map, entid_map, attribute_map, component_attributes: Vec::new() };
+        s.update_component_attributes();
+        s
+    }
+
     /// Returns an symbolic representation of the schema suitable for applying across Mentat stores.
     pub fn to_edn_value(&self) -> edn::Value {
         edn::Value::Vector((&self.attribute_map).iter()
@@ -840,6 +852,16 @@ impl Schema {
     fn get_raw_entid(&self, x: &NamespacedKeyword) -> Option<Entid> {
         self.ident_map.get(x).map(|x| *x)
     }
+
+    pub fn update_component_attributes(&mut self) {
+        let mut components: Vec<Entid>;
+        components = self.attribute_map
+                         .iter()
+                         .filter_map(|(k, v)| if v.component { Some(*k) } else { None })
+                         .collect();
+        components.sort_unstable();
+        self.component_attributes = components;
+    }
 }
 
 impl HasSchema for Schema {
@@ -876,6 +898,10 @@ impl HasSchema for Schema {
     fn identifies_attribute(&self, x: &NamespacedKeyword) -> bool {
         self.get_raw_entid(x).map(|e| self.is_attribute(e)).unwrap_or(false)
     }
+
+    fn component_attributes(&self) -> &[Entid] {
+        &self.component_attributes
+    }
 }
 
 #[cfg(test)]

db/src/metadata.rs

@@ -91,6 +91,13 @@ pub struct MetadataReport {
     pub idents_altered: BTreeMap<Entid, IdentAlteration>,
 }
 
+impl MetadataReport {
+    pub fn attributes_did_change(&self) -> bool {
+        !(self.attributes_installed.is_empty() &&
+          self.attributes_altered.is_empty())
+    }
+}
+
 /// Update a `AttributeMap` in place from the given `[e a typed_value]` triples.
 ///
 /// This is suitable for producing a `AttributeMap` from the `schema` materialized view, which does not
@@ -284,6 +291,10 @@ pub fn update_schema_from_entid_quadruples<U>(schema: &mut Schema, assertions: U
         idents_altered.insert(entid, IdentAlteration::Ident(ident.clone()));
     }
 
+    if report.attributes_did_change() {
+        schema.update_component_attributes();
+    }
+
     Ok(MetadataReport {
         idents_altered: idents_altered,
         .. report

db/src/schema.rs

@@ -241,12 +241,7 @@ impl SchemaBuilding for Schema {
         let entid_map: EntidMap = ident_map.iter().map(|(k, v)| (v.clone(), k.clone())).collect();
 
         validate_attribute_map(&entid_map, &attribute_map)?;
-
+        Ok(Schema::new(ident_map, entid_map, attribute_map))
-        Ok(Schema {
-            ident_map: ident_map,
-            entid_map: entid_map,
-            attribute_map: attribute_map,
-        })
     }
 
     /// Turn vec![(NamespacedKeyword(:ident), NamespacedKeyword(:key), TypedValue(:value)), ...] into a Mentat `Schema`.
@@ -258,8 +253,14 @@ impl SchemaBuilding for Schema {
             let attr: i64 = *ident_map.get(&symbolic_attr).ok_or(ErrorKind::UnrecognizedIdent(symbolic_attr.to_string()))?;
             Ok((ident, attr, value))
         }).collect();
+
         let mut schema = Schema::from_ident_map_and_attribute_map(ident_map, AttributeMap::default())?;
-        metadata::update_attribute_map_from_entid_triples(&mut schema.attribute_map, entid_assertions?)?;
+        let metadata_report = metadata::update_attribute_map_from_entid_triples(&mut schema.attribute_map, entid_assertions?)?;
+
+        // Rebuild the component attributes list if necessary.
+        if metadata_report.attributes_did_change() {
+            schema.update_component_attributes();
+        }
         Ok(schema)
     }
 }
@@ -327,6 +328,10 @@ mod test {
         schema.entid_map.insert(entid, ident.clone());
         schema.ident_map.insert(ident.clone(), entid);
 
+        if attribute.component {
+            schema.component_attributes.push(entid);
+        }
+
         schema.attribute_map.insert(entid, attribute);
     }
 

src/conn.rs

@@ -336,6 +336,10 @@ impl<'a, 'c> HasSchema for InProgressRead<'a, 'c> {
     fn identifies_attribute(&self, x: &NamespacedKeyword) -> bool {
         self.0.identifies_attribute(x)
     }
+
+    fn component_attributes(&self) -> &[Entid] {
+        self.0.component_attributes()
+    }
 }
 
 impl<'a, 'c> HasSchema for InProgress<'a, 'c> {
@@ -368,6 +372,10 @@ impl<'a, 'c> HasSchema for InProgress<'a, 'c> {
     fn identifies_attribute(&self, x: &NamespacedKeyword) -> bool {
         self.schema.identifies_attribute(x)
     }
+
+    fn component_attributes(&self) -> &[Entid] {
+        self.schema.component_attributes()
+    }
 }